The invention relates to a valve device for a heat exchanger located in a bypass in a cooling circuit, especially of an internal combustion engine. A valve body actuated as a function of delivery pressure against the resistance of a return spring relative to a valve seat to limit a line cross section, as well as a throttle passage serving for a predetermined coolant throughput are located in a housing of the valve device for through-flow-regulated pressure limitation.
A valve device of the type generally described above is known for example from German patent document DE 196 27 655 A, which is used for a heating device for a vehicle. The valve device is located in a bypass for heat exchangers to keep the feed pressure of the hot water at a constant level in each heat exchanger. In addition, the valve body used in the valve device has a throttle passage for the purpose of maintaining a hot water circulation in the bypass when the valve body is closed.
Another valve device of the type generally described above is known from European patent document EP-A 0 302 264. The subject of this reference is intended to provide maximum heat transfer in the heat exchanger located downstream, especially when the internal combustion engine is at idle. This is accomplished by the fact that the coolant throughput is almost not throttled at all when the engine is at idle. No additional information for higher pump pressures is provided.
The goal of the invention is to improve on the valve device of the type generally described above in such fashion that the feed and delivery pressures are limited when a coolant throughput is reached that produces maximum heat transfer in the heat exchanger with flow continuing through the heat exchanger. A delivery-dependent effective safety device is combined with this through-flow-regulated pressure demand.
This goal is achieved by providing a valve device for a heat exchanger located in a bypass cooling circuit of an internal combustion engine, comprising: a housing communicated with the bypass cooling circuit; a valve seat located in said housing, said valve seat defining a line cross section; a valve body disposed in said housing to be movable between a closed position engaged with said valve seat and an open position spaced from said valve seat, said valve body defining a throttle passage; a return spring arranged to bias said valve body toward said open position; said valve body being moved into said closed position by a delivery pressure of a coolant flow for a maximum heat transfer in the heat exchanger, said throttle passage having a cross-section adapted to said maximum heat transfer, wherein said valve body, in the event of a break in the bypass cooling circuit, serves as part of a break valve that is held in a closed position independently of the delivery pressure via a locking device, with a sealing element that suppresses the coolant flow.
This goal is achieved by providing a valve for a fluid line, comprising: a valve housing; a sliding sleeve slidably disposed in said housing, said sliding sleeve being slidable between an upstream position and a downstream position, said sliding sleeve defining a valve seat; a spring arranged between said sliding sleeve and said valve housing, said spring biasing said sliding sleeve toward said upstream position; a valve body disposed in said sliding sleeve to be movable between an open position and a closed position, said valve body defining a sealing seat which engages said valve seat in said closed position, said valve body defining a throttle passage; a return spring arranged between said valve body and said sliding sleeve, said return spring biasing said valve body toward said open position; a sealing element arranged downstream of said valve body, said sealing element sealing said throttle passage when said valve body is in said closed position and said sliding sleeve is in said downstream position.
In so-called thermomanagement systems with separate heat exchangers for heating and cooling, with the valve device according to the invention the flow through the respective heat exchanger can advantageously be limited continuously as a function of its maximum necessary coolant throughput for optimum heat transfer. With this individual pressure limitation for each individual heat exchanger in the bypass, it is also advantageously ensured that each heat exchanger at most has only the coolant throughput necessary for optimum heat transfer and therefore all of the heat exchangers in the cooling circuit, depending on their design, are supplied with the required maximum quantity of coolant when the valve body that limits the pressure is closed. As a result, the engine itself, especially with heat exchangers connected in parallel in the coolant circuit and additional heat exchangers also included in the circuit, is provided with more coolant for its own heating or cooling. With this pressure limitation set according to the invention for the coolant throughput for maximum heat transfer, with a coolant throughput through the throttle passage that corresponds to the respective throttle characteristic of the heat exchanger in question, in the event of a further increase in coolant throughput in the cooling circuit the heat exchanger is protected against an additional pressure rise and its operating safety is thus increased.
The valve device according to the invention, in addition to the pressure limitation achieved by using through-flow regulation, also serves as a first pipe or hose break valve known of itself for example from German patent document DE-8 1 172 918 whose through flow shutoff function in a motor vehicle with a liquid-cooled engine with heat exchangers included in bypasses in its cooling circuit for various purposes, in the event of a pipe or hose break, cuts off the affected bypass circuit from the rest of the cooling circuit, with the vehicle advantageously continuing to be operable.
In a first embodiment of the invention, the valve device is equipped with a pipe or hose break valve in such fashion that the valve body made with the throttle passage is slidably movably mounted in a sliding sleeve that contains the valve seat. The sleeve is mounted in the housing between the pipe and hose stubs, with the valve body abutting the valve seat essentially tightly as a function of delivery pressure, against a compression spring in tight contact with the housing. With the additional striking movement of the sliding sleeve triggered as a function of the delivery pressure by a tube or hose break, an elastic element in a fixed location downstream in the pipe or hose stub closes the throttle passage.
To maintain the function of a pipe or hose break valve especially when the delivery pressure or coolant throughput is low, it is proposed in another embodiment that when the throttle passage closes, a locking device operates that holds the valve body and the sliding sleeve in a tight closed position.
The improved safety valve according to the invention described above ensures that when a line break takes place downstream from the valve device in the bypass, a further escape or loss of coolant from the cooling circuit that is usually equipped with a circulating pump is avoided in conjunction with a check valve that serves in the bypass return as a pipe or hose break valve. Thus, in particular, a cooling circuit of an engine continues to function with the exception of the heat exchanger cut off by a broken line section.
In an embodiment of a combined pressure-limiting and safety valve designed differently from the valve device described above, it is proposed that in a housing, a diaphragm that separates a return chamber from a divided forward chamber with a partition that has a valve opening is in a driving connection with a valve body that controls the valve opening on the outflow side, with throttle passages and a valve plate that closes the valve opening in the event of a pipe or hose break on the feed side, and that a check valve is located in a return stub of the housing on the heat exchanger side.
A third valve device according to the invention is advantageously designed simply so that the valve body itself, in the event of a line break, serves as a pipe or hose break valve and thus only one separate pipe or hose break valve is necessary in the bypass in the other line.
With the design of the valve device advantageously first described in terms of construction cost and space, to achieve the safety function when a pipe or hose breaks, a corresponding delivery pressure is necessary in the cooling circuit. With the second design of the valve device that is slightly more expensive to build, the safety function is ensured by a closing spring that acts on the diaphragm on the return chamber side.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.